Yeah, he did have the ability to turn on and off his invulnerability, as the shield was always up but he had the ability to manipulate it, he could even throw it in front of someone to shield them.So it's likely he just turned it off so that it could be pierced.

" Yeah, he did have the ability to turn on and off his invulnerability, as the shield was up but he had the ability to manipulate it, he could even throw it in front of someone to shield them. So it's likely he just turned it off so that it could be pierced. "